1. Technical Field
The present invention relates to a speed reducer that is used to drive a wheel of a vehicle.
The present application claims priority on Japanese Patent Application No. 2011-227157 filed on Oct. 14, 2011, the entire contents of which are incorporated herein by reference.
2. Description of the Related Art
A speed reducer, which is used to drive a wheel of a vehicle, is disclosed in International Publication WO 00/36317 (FIG. 1).
This speed reducer includes a parallel shaft gear mechanism that includes a parallel shaft gear, and a planetary gear mechanism that is provided on a rear stage of the parallel shaft gear mechanism and includes planetary gears and an internal gear with which the planetary gears internally mesh. Further, apart of the speed reducer is disposed within a wheel.